So my car is leaking oil in two places...the front crank seal and the rear main seal. Looks like a common thing with high mileage M54's. The front seems pretty straight forward from what I read, but I am debating doing the rear main seal, or whether i should just let it be and add oil as it needs it. So lets say I replace the seal, I know it requires dropping the transmission, and I am curious if anyone has done this job, or if I should just take it somewhere and have it done...any insight/advice/guidance on this would be much appreciated! Thanks!
Have you checked your crankcase pressure? Because if the valve is stuck then it will blow out seals in your engine and if your replace the seals without fixing the oil separator it will just blow them out again. To replace front crank seal isn't that bad the rear requires more work. Dropping a trans is never really easy especially if you don't have a lift to do it on. Personally if you don't have a lift I wouldn't tackle it yourself not one you wanna do on jack stands.
I did my manual E34 on jack stands - it was a hassle, but I worked it out. A lift is sooooooo much easier! It's a big job though for any car - exhaust out, heat shields off, driveshaft out, and transmissions are heavy, awkward, and bulky - and you don't want to damage it. And then just that many more particulars to address all along. Get a Bentley Manual for your car if you don't already have one, quite helpful. Different car, trans, & jacking points, etc., but here's a couple of posts about generally what you'd be facing, perhaps help to make the decision whether dropping a transmission is something you want to tackle. http://www.bmwcca.org/forum/index.php?threads/for-the-e32-lovers-a-5-spd-for-sale.7560/#post-57328 http://www.bmwcca.org/forum/index.php?threads/for-the-e32-lovers-a-5-spd-for-sale.7560/#post-57344